CN1096428C - Method of fabricating dispersion mobile optical fiber with smooth annular ring refractive index profile - Google Patents

Abstract

The method of manufacturing a dispersed moving optical fiber with a smooth annular refractive index profile comprises the steps of: heating the quartz tube with an external oxygen or hydrogen burner to increase the temperature from 1875°C to 1903°C, feeding the quartz tube, depositing the first skin layer; At a constant temperature of 1900°C, feed the raw material to deposit the annular part; raise the temperature from 1890°C to 1897°C, feed the material at the same time, deposit the second skin layer; heat in nine processes from 1920°C to 1890°C, depositing the core part; and condensing the deposited optical fiber at 2300-2360° C., and sealing.

Description

Manufacturing method of dispersed moving optical fiber with smooth annular refractive index profile

The present invention relates to dispersed moving optical fibers, and more particularly, the present invention relates to dispersed moving optical fibers having an annular refractive index distribution around a core member lower than that of the core member and a method of manufacturing the same by injecting a chemical gas into a quartz tube The MCVD method smoothes the index of refraction and heats the external burner for deposition, making the geometry of the optical fiber uniform.

This application is based on Korean Application No. 40089/1995, which is incorporated herein by reference.

Recently, the variety and performance of dispersed mobile optical fibers (using 1.55 μm quartz optical fibers for high-speed information networks) have changed. The variety and performance of the dispersed mobile optical fiber have been described in detail in the reference ("OPTICAL FIBER TELECOMMUNICATION II" published in Academic Press, Inc., Pages 29-36), and this specification will omit it. Non-dispersive migrating optical fibers, in particular, dispersive migrating optical fibers with annular refractive index profiles are well known because of their good microbending losses. The optical fiber of this structure was proposed by Mr.Bhagavatula and his colleagues in 1983, disclosed in US4412722 (1983) and US4516826 (1984) respectively, it is reported that it has a layer around the core to protect the core low ring refractive index. It is mainly manufactured by OVD (Outside Vapor Deposition) and MCVD (Modified Chemical Vapor Deposition). That is, it is difficult to manufacture an optical fiber having a stepped annular refractive index distribution structure (disclosed in US4715679, KR26410, and KR49509) by OVD, although it is easy to manufacture an optical fiber having a triangular annular distribution structure, or it is also easy to manufacture a base A porous structure with a relatively large outer diameter to some extent. However, MCVD makes it easy to manufacture optical fibers of any desired distribution due to uniform flow control by in-deposition (as described in US4737179, US4755022 and US4822399), but it cannot produce optical fibers with a base material having a large outer diameter.

Referring to the system of Figure 1, the prior art of Figures 2 and 3 illustrate that a constant amount of raw gas is fed from the raw gas supply system to a quartz tube heated to a constant temperature by a burner, resulting in the manufacture of dispersed moving Optical fiber. To explain the above manufacturing method in more detail, before depositing the first skin layer, the light heats the quartz tube for a specified time, so that the surface temperature of the quartz tube reaches 1890 ° C, so that the inside of the quartz tube is uniform, and then the external oxygen or hydrogen is used to The burner continued heating at 1890°C while supplying 5400mg/min of SiCl ₄ , 450mg/min of GeCl ₄ , 40mg/min of POCl ₃ and 12cc/min of CF ₄ (as shown in Figures 3B-3F). Thereafter, 3000 mg/min of _SiCl4 , 1300 mg/min of _GeCl4 , 35 mg/min of _POCl3 and 2000 cc/min of _O2 were supplied into the quartz tube and uniformly heated to not more than 1905°C to deposit the annular portion, as shown in Fig. 3A. Then, 4000 mg/min SiCl ₄ , 450 mg/min GeCl ₄ , 25 mg/min POCl ₃ and 9 cc/min CF ₄ were fed into the quartz tube and uniformly heated to 1915° C. to form the second skin layer (as shown in FIG. 3A ). Besides, 1100 mg/min of _SiCl4 and 2000 mg/min of _O2 were fed into the quartz tube, and _GeCl4 was added so as not to exceed 60-250 mg/min while uniformly heating the tube at 1910C to deposit the core part. The optical fiber deposited in the quartz tube was condensed at 2300-2320°C, and 30-40cc/min of _CF4 was added to the condensed optical fiber. Finally, it is etched at 2220-2250°C and heated to 2340-2360°C to make it tightly sealed and closed, as shown in Figure 3A.

The prior art described above has an annular distribution of dispersed moving optical fibers whose core members have a conical refractive index. For the maximum refractive index at the center of the core, the amount of _GeO2 must be increased up to the center of the core. However, in the MCVD method, during the _GeO2 addition, it causes a center drop problem, that is, a decrease in the refractive index occurs during the deposition process and at the center of the core.

The above-mentioned optical fiber has another problem in that when the base material is obtained from the optical fiber, since the diameter of the core member is small compared with the ordinary single-mode optical fiber, the optical properties deviate greatly along the length of the base material in the optical fiber.

One object of the present invention is by adjusting the deposition temperature and the deposition feed _flow in the base material precipitation process, and by adding a given amount of SF ₆ and CF ₄ in GeO ₂ Volatilize at the center of the wick) to reduce center dip, thereby providing a means of causing a non-waveform refractive index.

Another object of the present invention is to provide a method of making the diameter of the core member uniform by increasing the outer diameter of the base material.

According to the present invention, the manufacturing method of the dispersed moving optical fiber with smooth annular refractive index distribution comprises the following steps: (a) heating the quartz tube with an external oxygen or hydrogen burner to increase its temperature from 1875°C to 1903°C, Tube supply raw materials, including 5200mg/min SiCl ₄ , 430mg/min GeCl ₄ , 30mg/min POCl ₃ and 9CC/min CF ₄ , to deposit the first skin layer; (b) at a constant temperature of 1900°C, supply raw materials including 3300 mg/min SiCl ₄ , 1150 mg/min GeCl ₄ , 20 mg/min POCl ₃ and 1500 cc/min O ₂ to deposit the annular part; (c) increase the temperature from 1890°C to 1897°C while supplying raw materials including 3800mg/min SiCl ₄ , 430 mg/min GeCl ₄ , 10 mg/min POCl ₃ and 7 cc/min CF ₄ to deposit the second skin layer; (d) heating during nine ramps from 1920°C to 1890°C to deposit the core Parts, in these nine processes, the feed flow of SiCl ₄ is reduced from 380mg/min to 260mg/min, and in these nine processes, the feed flow of GeCl ₄ is increased from 20mg/min to 195mg/min, and in these nine processes During this process, the O _feed flow rate remains constant at 1500cc/min; and (e) condenses the deposited optical fiber at 2300-2360°C, and 30-40cc/ _min CF is added to the quartz tube at 2220-2250°C. ℃ etching, and add 100cc/min Cl ₂ to the quartz tube at 2350-2370℃ to seal and seal.

Fig. 1 is the schematic diagram of common MCVD manufacturing method;

Fig. 2 is the circular distribution of prior art;

Fig. 3 A represents the heating temperature of each process in the manufacturing method of conventional annular distribution;

Fig. 3 B represents the _SiCl of supplying each process in the manufacturing method of conventional annular distribution Feed flow rate;

Fig. 3 C represents the feed flow rate of _GeCl supplied to each process in the manufacturing method of conventional annular distribution;

Figure 3D represents the _POCl3 feed flow rate supplied to each process in a conventional annular distribution manufacturing process;

Figure 3E represents the O _feed flow rates supplied to each process in a conventional annular distribution manufacturing process;

Figure 3F represents the _CF4 ( _SF6 ) feed flow rate for each process in a conventional annular distribution manufacturing process;

Fig. 4 is the annular distribution of the present invention;

Fig. 5 A shows the heating temperature of each process in the manufacturing method of the smooth annular refractive index distribution according to the present invention;

Fig. 5 B represents the _SiCl feed flow rate supplied to each process in the smooth annular refractive index profile manufacturing method of the present invention;

Fig. 5 C shows the _GeCl feed flow rate supplied to each process in the smooth annular refractive index profile manufacturing method of the present invention;

Figure 5D shows the _POCl3 feed flow rate supplied to each process in the smooth annular refractive index profile manufacturing method of the present invention;

Figure 5E shows the O _feed flow rates supplied to each process in the smooth annular refractive index profile manufacturing method of the present invention;

Fig. 5F shows the feed flow rate of CF ₄ (SF ₆ ) supplied to each process in the smooth annular refractive index profile manufacturing method according to the present invention; and

FIG. 5G shows the _Cl2 feed flow rate to each process in the smooth annular refractive index profile manufacturing method according to the present invention.

Fig. 1 illustrates that while a quartz tube is heated by a burner at a constant temperature, a specified amount of raw material gas is supplied to the quartz tube through a raw material gas supplier to manufacture a dispersed moving optical fiber having a ring-shaped refractive index. The above method is described in detail as follows: the quartz tube is heated until its surface temperature is 1875° C., and maintained for a certain period of time, so that the inner surface temperature is uniform, as shown in FIG. 5A . Then, as shown in Figure 5B-5G, the quartz tube was heated with an external oxygen or hydrogen burner, and its temperature was increased from 1875 ° C to 1903 ° C in nine processes, and the temperature was increased by 3.5 ° C. At the same time, 5200 mg/min SiCl was supplied _4. 430 mg/min GeCl ₄ , 30 mg/min POCl ₃ and 9 cc/min CF ₄ to deposit the first skin layer. To deposit the annular portion, as shown in Figure 5A, 3300 mg/min _SiCl4 , 1150 mg/min GeCl4, ₂₀ mg/min POCl3 and ₁₅₀₀ cc/min _O2 were supplied at a constant deposition temperature of 1900°C. Next, in order to prepare the second skin layer, supply raw materials into the quartz tube, including 3800mg/min SiCl ₄ , 430mg/min GeCl ₄ , 10mg/min POCl ₃ and 7cc/min CF ₄ (as shown in Figures 5B-5G), while making The temperature was increased from 1890°C to 1897°C (as shown in Figure 5A). Finally, in the nine passes of Figure 5A, the deposition temperature was lowered from 1920°C to 1890°C to deposit the core portion. Simultaneously, the feed flow rate of SiCl ₄ was reduced from 380 mg/min to 260 mg/min in nine processes, the feed flow rate of GeCl ₄ was increased from 20 mg/min to 195 mg/min in nine processes, and O ₂ in nine processes The feed flow was kept constant at 1500 cc/min. For this purpose, the raw material feed flows are shown in Table 1.

Table 1 process 1 2 3 4 5 6 7 8 9 SiCl ₄ (mg/min) 380 365 350 335 320 305 290 275 260 GeCl ₄ (mg/m) 20 52 82 109 134 156 175 191 195 T(°C) 1920 1916 1913 1909 1905 1901 1897 1894 1890

Then, the deposited optical fiber was condensed at 2300-2360° C. as shown in FIG. 5A , and 30-40 cc/min of CF ₄ was added into the quartz tube (as shown in FIG. 5F ). After etching at 2220-2250°C, 100cc/min _Cl2 was supplied to the quartz tube (as shown in Figure 5G) while heating at 2350-2370°C (as shown in Figure 5A) to seal and seal.

In another embodiment of the present invention, the deposition temperature was reduced from 1905°C to 1890°C in nine passes to deposit core portions. At the same time, the feed flow rate of _SiCl4 in the nine processes is reduced from 300mg/min to 260mg/min, the feed flow rate of _GeCl4 in the nine processes is increased from 20mg/min to 195mg/min, and the flow rate of _O2 in the nine processes is increased. The material flow remains constant at 1500cc/min. For this purpose, the raw material feed flows are shown in Table 2.

Table 2 process 1 2 3 4 5 6 7 8 9 SiCl ₄ (mg/min) 300 295 290 285 280 275 270 265 260 GeCl ₄ (mg/m) 20 42 67 92 116 138 160 182 195 T(°C) 1905 1903 1900 1898 1895 1893 1890 1890 1890

In yet another embodiment of an invention, the deposition temperature was reduced from 1905°C to 1890°C in nine passes to deposit core portions. At the same time, the feed flow rate of _SiCl4 in the nine processes was reduced from 300mg/min to 260mg/min, the feed flow rate of _GeCl4 in the nine processes was increased from 30mg/min to 195mg/min, and the feed flow rate of _O2 in the nine processes was Keep 1500ccm/min unchanged. For this purpose, the raw material feed flows are shown in Table 3.

table 3 process 1 2 3 4 5 6 7 8 9 SiCl ₄ (mg/min) 300 296 290 285 280 275 270 265 260 GeCl ₄ (mg/m) 30 55 78 101 123 144 165 184 195 T(°C) 1905 1903 1900 1898 1895 1893 1890 1890 1890

As mentioned above, the present invention is by adjusting the deposition temperature and the deposition feed flow rate in the base material deposition process, and adds the specified amount of SF ₆ and CF ₄ in GeO ₂ , (GeO ₂ is at high temperature in the base material sealing and sealing process volatilization at the center of the wick) to reduce the center drop, thereby providing a means of causing a non-waveform refractive index. In addition, the present invention provides a method of making the diameter of the core member uniform by increasing the outer diameter of the base material by the overcladding method. Therefore, the present invention is advantageous in that it enables improved optical fiber loss and has very stable color dispersion properties.

Therefore, it should be understood that this invention is not limited to the particular embodiment disclosed herein as the best mode for carrying out this invention, nor is it limited to the particular embodiment described in this specification except as described in the appended claims. beyond the limits.

Claims (3)

1. the manufacture method of a dispersion mobile optical fiber, it comprises the steps:

With external firing device heated quarty tube, provide the temperature that rises to 1903 ℃ from 1875 ℃ to described silica tube, simultaneously to the silica tube base feed, comprise 5200mg/ minute SiCl ₄, 430mg/ minute GeCl ₄, 30mg/ minute POCl ₃With 9cc/ minute CF ₄, deposit first cortex;

Make the described temperature of described silica tube remain on about 1900 ℃ steady temperature, simultaneously feeding comprises 3300mg/ minute SiCl ₄, 1150mg/ minute GeCl ₄, 20mg/ minute POCl ₃With 1500cc/ minute O ₂Feed rate, the deposition circular part;

Heat described silica tube, the temperature of described silica tube is brought up to 1897 ℃ from 1890 ℃, simultaneously feeding comprises 3800mg/ minute SiCl ₄, 430mg/ minute GeCl ₄, 10mg/ minute POCl ₃With 7cc/ minute CF ₄Feed rate, deposit second cortex;

The described silica tube of heating in nine temperature reduction processes is respectively with 1920 ℃, 1916 ℃, 1913 ℃, 1909 ℃, 1905 ℃, 1901 ℃.1897 ℃, 1894 ℃ and 1890 ℃ provide described temperature, simultaneously in described nine processes respectively with the minimizing feed rate supply SiCl of 380mg/ minute, 365mg/ minute, 350mg/ minute, 335mg/ minute, 320mg/ minute, 305mg/ minute, 290mg/ minute, 275mg/ minute and 260mg/ minute ₄, in described nine processes respectively with the feed rate supply GeCl of 20mg/ minute, 52mg/ minute, 82mg/ minute, 109mg/ minute, 134mg/ minute, 156mg/ minute, 175mg/ minute, 191mg/ minute and 195mg/ minute ₄, and the constant feed flow with 1500cc/ minute is supplied O in described nine processes ₂, deposition chipware part;

Heat described silica tube, in 2300-2360 ℃ of temperature range, provide described temperature, simultaneously to the feed rate supply CF of described silica tube with 30-40cc/ minute ₄, the described silica tube of condensation;

Heat described silica tube, in 2220-2250 ℃ of temperature range, provide described temperature, carry out etching;

To 100cc/ minute Cl of described silica tube supply ₂, heat described silica tube simultaneously, in 2350-2370 ℃ of temperature range, provide described temperature, seal.

2. the manufacture method of a dispersion mobile optical fiber, it comprises the steps:

With external firing device heated quarty tube, provide the temperature that rises to 1903 ℃ from 1875 ℃ to described silica tube, simultaneously to the silica tube base feed, comprise 5200mg/ minute SiCl ₄, 430mg/ minute GeCl ₄, 30mg/ minute POCl ₃With 9cc/ minute CF ₄, deposit first cortex;

Make the described temperature of described silica tube remain on about 1900 ℃ steady temperature, simultaneously feeding comprises 3300mg/ minute SiCl ₄, 1150mg/ minute GeCl ₄, 20mg/ minute POCl ₃With 1500cc/ minute O ₂Feed rate, the deposition circular part;

Heat described silica tube, the temperature of described silica tube is brought up to 1897 ℃ from 1890 ℃, simultaneously feeding comprises 3800mg/ minute SiCl ₄, 430mg/ minute GeCl ₄, 10mg/ minute POCl ₃With 7cc/ minute CF ₄Feed rate, deposit second cortex;

The described silica tube of heating in nine temperature reduction processes is respectively with 1905 ℃, 1903 ℃, 1900 ℃, 1898 ℃, 1895 ℃, 1893 ℃.1890 ℃, 1890 ℃ and 1890 ℃ provide described temperature, simultaneously in nine processes respectively with the minimizing feed rate supply SiCl of 300mg/ minute, 295mg/ minute, 290mg/, 285mg/ minute, 280mg/ minute, 275mg/ minute, 270mg/ minute, 265mg/ minute and 260mg/ minute ₄, in described nine processes respectively with the feed rate supply GeCl of 20mg/ minute, 42mg/ minute, 67mg/ minute, 92mg/ minute, 116mg/ minute, 138mg/ minute, 160mg/ minute, 182mg/ minute and 195mg/ minute ₄, and the constant feed flow with 1500cc/ minute is supplied O in described nine processes ₂, deposition chipware part;

Heat described silica tube, in 2300-2360 ℃ of temperature range, provide described temperature, simultaneously to the feed rate supply CF of described silica tube with 30-40cc/ minute ₄, the described silica tube of condensation;

Heat described silica tube, in 2220-2250 ℃ of temperature range, provide described temperature, carry out etching;

To 100cc/ minute Cl of described silica tube supply ₂, heat described silica tube simultaneously, in 2350-2370 ℃ of temperature range, provide described temperature, seal.

3. the manufacture method of a dispersion mobile optical fiber, it comprises the steps:

With external firing device heated quarty tube, provide the temperature that rises to 1903 ℃ from 1875 ℃ to described silica tube, simultaneously to described silica tube base feed, comprise 5200mg/ minute SiCl ₄, 430mg/ minute GeCl ₄, 30mg/ minute POCl ₃With 9cc/ minute CF ₄, deposit first cortex;

The described temperature of described silica tube is remained under about 1900 ℃ steady temperature, and simultaneously feeding comprises 3300mg/ minute SiCl ₄, 1150mg/ minute GeCl ₄, 20mg/ minute POCl ₃With 1500cc/ minute O ₂Feed rate, the deposition circular part;

Heat described silica tube, the temperature people of described silica tube is brought up to 1897 ℃ for 1890 ℃, simultaneously feeding comprises 3800mg/ minute SiCl ₄, 430mg/ minute GeCl ₄, 10mg/ minute POCl ₃With 7cc/ minute CF ₄Feed rate, deposit second cortex;

The described silica tube of heating in nine temperature reduction processes is respectively with 1905 ℃, 1903 ℃, 1900 ℃, 1898 ℃, 1895 ℃, 1893 ℃.1890 ℃, 1890 ℃ and 1890 ℃ provide described temperature, simultaneously in described nine processes respectively with the minimizing feed rate supply SiCl of 300mg/ minute, 295mg/ minute, 290mg/ minute, 285mg/ minute, 280mg/ minute, 275mg/ minute, 270mg/ minute, 265mg/ minute and 260mg/ minute ₄, in described nine processes respectively with the feed rate supply GeCl of 30mg/ minute, 55mg/ minute, 78mg/ minute, 101mg/ minute, 123mg/ minute, 144mg/ minute, 165mg/ minute, 184mg/ minute and 195mg/ minute ₄, and the constant feed flow with 1500cc/ minute is supplied O in described nine processes ₂, deposition chipware part;

Heat described silica tube, in 2300-2360 ℃ of temperature range, provide described temperature, simultaneously to the feed rate supply CF of described silica tube with 30-40cc/ minute ₄, the described silica tube of condensation;

Heat described silica tube, in 2220-2250 ℃ of temperature range, provide described temperature, carry out etching;

To 100cc/ minute Cl of described silica tube supply ₂, heat described silica tube simultaneously, in 2350-2370 ℃ of temperature range, provide described temperature, seal.

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